KR20120032032A - Method and apparatus for transparent relay hybrid automatic repeat request (harq) - Google Patents

Abstract

Systems, apparatus, and methods for a relay station for use in a communication system having a base station and a user equipment (UE) are disclosed. The relay station may decode and forward data packets between the base station and the UE being served by the relay station, where the relay station does not establish a direct link with the UE. In addition, if the base station receives information indicating successful decoding of the data packet from the relay station, the base station terminates HARQ transmission on the direct link between the base station and the UE, thereby reducing the HARQ retransmission time compared to the direct communications between the base station and the UE. Indicates successful decoding of the data packet to the base station so that it is extended.

Description

METHODS AND APPARATUS FOR TRANSPARENT RELAY HYBRID AUTOMATIC REPEAT REQUEST (HARQ)}

This application is incorporated by reference in 35 U.S.C. Claims under 119 (e), which application is specifically incorporated herein by reference in its entirety.

Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and the like. Such systems may be multiple access systems capable of supporting communication with multiple users by sharing available system resources (eg, bandwidth and transmit power). Examples of such multiple access systems are code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems 3GPP Long Term Evolution (LTE) systems and Orthogonal Frequency Division Multiple Access (OFDMA) systems.

In general, a wireless multiple-access communication system may simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. Such a communication link may be established through a single input single output, multiple input single output or multiple input multiple output (MIMO) system.

To complement conventional mobile phone network base stations, additional base stations can be deployed to provide more robust wireless coverage for mobile units. For example, wireless relay stations and small coverage base stations (eg, access point base stations, home NodeBs, femto access) for gradual capacity growth, richer user experience, and in-building coverage. Points or femto cells) may be deployed. Typically, these small coverage base stations are connected to the Internet and mobile operator's network via a DSL router or cable modem. Since these other types of base stations can be added to a conventional mobile telephone network (eg backhaul) in a different manner than conventional base stations (eg macro base stations), these other types of base stations and their There is a need for effective techniques for managing associated user equipment.

Systems, apparatus, and methods for a relay station for use in a communication system having a base station and a user equipment (UE) are disclosed. The relay station may decode and forward data packets between the base station and the UE being served by the relay station, where the relay station does not establish a direct link with the UE. In addition, if the base station receives information indicating successful decoding of the data packet from the relay station, the base station terminates HARQ transmission on the direct link between the base station and the UE, thereby reducing the HARQ retransmission time compared to the direct communications between the base station and the UE. Indicates successful decoding of the data packet to the base station so that it is extended.

The features, nature and advantages of the present disclosure will become more apparent from the following detailed description when considered in conjunction with the drawings in which like reference numerals correspondingly identify throughout.
1 illustrates a multiple access wireless communication system according to one embodiment.
2 shows a block diagram of a communication system.
3 illustrates an example communication system for enabling deployment of access point base stations within a network environment.
4 shows a wireless communication system, which may be an LTE system or any other wireless system using a relay station.
5 shows a block diagram of a design of a base station / eNB, relay station and UE.
6 shows a block diagram of a method for applying HARQ procedures for transparent relays to a relay station.
7 is a flowchart illustrating a process for applying HARQ procedures for transparent relays to a relay station.
8 shows a block diagram for a method for enabling an anchor base station to schedule two transmissions, one transmission for a UE and another transmission for a relay station, for each UL transmission.
9 shows a block diagram of a method for applying asynchronous HARQ procedures for downlink (DL).
10 is a flowchart illustrating a process for applying HARQ procedures for downlink (DL).

등과 같은 무선 기술을 구현할 수 있다. UTRA, E-UTRA 및 GSM은 범용 이동 통신 시스템(UMTS: Universal Mobile Telecommunication System)의 일부이다. 롱 텀 에볼루션(LTE: Long Term Evolution)은 E-UTRA를 사용하는 UMTS의 향후 릴리스(release)이다. UTRA, E-UTRA, GSM, UMTS 및 LTE는 "3세대 파트너쉽 프로젝트"(3GPP)로 명명된 조직으로부터의 문서들에 기술되어 있다. cdma2000은 "3세대 파트너쉽 프로젝트 2"(3GPP2)로 명명된 조직으로부터의 문서들에 기술되어 있다. 이러한 다양한 무선 기술들 및 표준들은 해당 기술분야에 공지되어 있다. 명확성을 위해, 이러한 기술들의 특정 양상들은 LTE에 대해 아래에서 설명되며, 아래 설명의 대부분에는 LTE 용어가 사용된다.The techniques described herein include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) It can be used in various wireless communication networks such as: Single-Carrier FDMA) networks. The terms "networks" and "systems" are often used interchangeably. CDMA networks may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, and the like. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR). cdma2000 covers IS-2000, IS-95 and IS-856 standards. TDMA networks may implement wireless technologies such as Global System for Mobile Communications (GSM). OFDMA networks are Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM

Wireless technology such as UTRA, E-UTRA and GSM are part of the Universal Mobile Telecommunication System (UMTS). Long Term Evolution (LTE) is a future release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 is described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). These various radio technologies and standards are known in the art. For clarity, certain aspects of these techniques are described below for LTE, and LTE terminology is used in much of the description below.

There is a technique called single carrier frequency division multiple access (SC-FDMA) using single carrier modulation and frequency domain equalization. SC-FDMA has similar performance and essentially the same overall complexity as an OFDMA system. SC-FDMA signals have a lower peak-to-average power ratio (PAPR) because of their inherent single carrier structure. SC-FDMA has been of particular interest in uplink communications where lower PAPR greatly benefits the mobile terminal in terms of transmit power efficiency. This is currently a working assumption for the uplink multiple access scheme of 3GPP Long Term Evolution (LTE) or Evolved UTRA.

1, a multiple access wireless communication system according to one embodiment is described. Access point 100 (AP) includes a plurality of antenna groups, one antenna group includes 104 and 106, another antenna group includes 108 and 110, and additional antenna groups 112 and 114 It includes. In FIG. 1, only two antennas are shown per antenna group, although more or fewer antennas may be used per antenna group. An access terminal (AT) communicates with the antennas 112, 114, where the antennas 112, 114 transmit information to the access terminal 116 over the forward link 119 and reverse Receive information from access terminal 116 via link 118. The access terminal 130 communicates with the antennas 106 and 108, where the antennas 106 and 108 transmit information to the access terminal 130 via the forward link 126 and through the reverse link 124. Receive information from access terminal 130. In an FDD system, communication links 118, 119, 124, 126 may use different frequencies for communication. For example, the forward link 119 may use a different frequency than that used by the reverse link 118.

Each group of antennas and / or the area in which they are designated to communicate is often referred to as a sector of the access point. In an embodiment, each of the antenna groups is designed to communicate to access terminals in a sector of the areas covered by the access point 100.

In communication over forward links 119, 126, the transmit antennas of access point 100 use beamforming to improve the signal-to-noise ratio of the forward links for different access terminals 116, 130. In addition, an access point that uses beamforming to transmit to access terminals randomly scattered throughout its coverage may access the access terminals of neighboring cells as compared to the access point transmitting to all its access terminals via a single antenna. Cause less interference.

An access point may be a fixed station used to communicate with terminals, and may also be referred to as an access point, Node B, Evolved Node B (eNB), or some other terminology. An access terminal may also be referred to as an access terminal, user equipment (UE), wireless communication device, terminal, access terminal, or some other terminology.

2 is a block diagram of an embodiment of a transmitter system 210 (also known as an access point) and a receiver system 250 (also known as an access terminal) in the MIMO system 200. In the transmitter system 210, traffic data for multiple data streams is provided from a data source 212 to a transmit (TX) data processor 214.

In an embodiment, each data stream is transmitted via a respective transmit antenna. TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for each data stream to provide coded data.

Coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is a known data pattern that is typically processed in a known manner and can be used in the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (e.g., based on a particular modulation scheme selected for each data stream (e.g., BPSK, QPSK, M-PSK, or M-QAM). For example, symbol mapping) provides modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by the processor 230. [

Modulation symbols for all data streams are then provided to the TX MIMO processor 220, which may further process the modulation symbols (eg, for OFDM). TX MIMO processor 220 then provides N _T modulation symbol streams to N _T transmitters (TMTR) 222a-222t. In certain aspects, TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antenna, from which a symbol is being transmitted.

Each transmitter 222 receives and processes each symbol stream to provide one or more analog signals, and further adjusts (eg, amplifies, filters, and upconverts) the analog signals to modulate for transmission over a MIMO channel. To provide the specified signal. Then, N _T modulated signals from transmitters (222a-222t) are respectively transmitted from N _T antennas (224a-224t).

In receiver system 250, the transmitted modulated signals are received by N _R antennas 252a-252r, and the received signal from each antenna 252 is provided to each receiver (RCVR) 254a-254r. do. Each receiver 254 adjusts (e.g., filters, amplifies, and downconverts) each received signal, digitizes the adjusted signal to provide samples, and further processes the samples to correspond to the corresponding "receive" symbol stream. To provide.

Then, and it provides RX data processor 260 N _R received symbols streams received and processed N _R of "detected" symbol streams to a from the N _R receivers 254 based on a particular receiver processing technique. RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. Processing by the RX data processor 260 is complementary to that performed by the TX MIMO processor 220 and the TX data processor 214 in the transmitter system 210.

Processor 270 periodically determines which precoding matrix (discussed later) to use. Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion.

The reverse link message may include various types of information regarding the communication link and / or the received data stream. The reverse link message is then processed by TX data processor 238, which also receives traffic data for multiple data streams from data source 236, modulated by modulator 280, and transmitted by transmitters 254a-. 254r, and transmitted back to the transmitter system 210.

In transmitter system 210, modulated signals from receiver system 250 are received by antennas 224 and extract receivers 222 to extract a reverse link message sent by receiver system 250. Are demodulated by demodulator 240 and processed by RX data processor 242. Processor 230 then determines which precoding matrix to use to determine the beamforming weights, and then processes the extracted message.

3 illustrates an example communication system for enabling deployment of access point base stations within a network environment. As shown in FIG. 3, system 300 may include multiple access point base stations, or alternatively femto cells, or home node B units (HNBs) such as, for example, HNBs 310 or home evolved node. B units (HeNBs), each of which is installed in a corresponding small network environment, such as, for example, one or more user residences 330, as well as an alien, as well as associated user equipment (UE) or mobile station. Are also configured to serve the field 320. Each HNB 310 also connects to the Internet 340 and mobile operator core network 350 and to macro cell access 345 via a DSL router (not shown), or alternatively a cable modem (not shown). do.

4 shows a wireless communication system 101, which may be an LTE system or any other wireless system using a relay station. System 101 may include multiple evolved Node Bs (eNBs), relay stations, and other system entities capable of supporting communication for multiple UEs. An eNB may be a station that communicates with UEs and may be referred to as a base station, Node B, access point, or the like. The eNB may provide communication coverage for a particular geographic area. The term “cell” in 3GPP may refer to the coverage area of an eNB and / or the eNB subsystem serving this coverage area, depending on the context in which the term is used. An eNB may support one or multiple (eg, three) cells.

The eNB may provide communication for macro cells, pico cells, femto cells, and / or other types of cells. The macro cell may cover a relatively large geographic area (eg, several kilometers in radius) and may allow unlimited access by UEs with a service subscription. The pico cell may cover a relatively small geographic area and may allow unlimited access by UEs with a service subscription. A femto cell may cover a relatively small geographic area (eg, a home) and may be used for UEs associated with a femto cell (eg, UEs in a Closed Subscriber Group (CSG)). Limited access can be allowed. The eNB for the macro cell may be referred to as a macro eNB. An eNB for a pico cell may be referred to as a pico eNB. The eNB for the femto cell may be referred to as a femto eNB or a home eNB. In FIG. 4, eNB 110 may be a macro eNB for macro cell 103, eNB 115 may be a pico eNB for pico cell 105, and eNB 117 may be a femto cell 107. It may be a femto eNB for. System controller 140 may be connected to a set of eNBs and may provide coordination and control for such eNBs.

Relay station 120 receives the transmission of data and / or other information from an upstream station (eg, eNB 110 or UE 130) and transmits a downstream station (eg, UE 130 or eNB 110). It may be a station that transmits transmission of data and / or other information in b)). The relay station may also be referred to as a relay, relay eNB, and the like. The relay station may also be a UE relaying transmissions to other UEs. In FIG. 4, relay station 120 may communicate with eNB 110 and UE 130 to facilitate communication between eNB 110 and UE 130.

UEs 130, 133, 135, 137 may be distributed throughout the system, and each UE may be stationary or mobile. The UE may also be referred to as a terminal, mobile station, subscriber unit, station, or the like. The UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless telephone, a wireless local loop (WLL) station, or the like. The UE may communicate with eNBs and / or relay stations on the downlink and uplink. The downlink (or forward link) refers to the communication link from the eNB to the relay station or from the eNB or relay station to the UE. The uplink (or reverse link) refers to the communication link from the UE to the eNB or relay station or from the relay station to the eNB. In FIG. 4, the UE 133 may communicate with the eNB 110 via the downlink 123 and the uplink 125. UE 130 may communicate with relay station 120 via an access downlink 153 and an access uplink 155. Relay station 120 may communicate with eNB 110 via backhaul downlink 143 and backhaul uplink 145.

In general, an eNB may communicate with any number of UEs and any number of relay stations. Likewise, a relay station can communicate with any number of eNBs and any number of UEs. For simplicity, much of the description below relates to communication between eNB 110 and UE 130 via relay station 120.

LTE uses Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and Single Carrier Frequency Division Multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the frequency range into multiple (N _FFT ) orthogonal subcarriers, which are also commonly referred to as tones, bins, and the like. Each subcarrier may be modulated by data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be constant, and the total number of subcarriers (N _FFT ) may depend on the system bandwidth. For example, the N _FFT may be equal to 128, 256, 512, 1024 or 2048 for a system bandwidth of 1.25, 2.5, 5, 10 or 20 megahertz (MHz), respectively.

The system can use FDD or TDD. In the case of FDD, separate frequency channels are assigned to the downlink and uplink. Downlink transmissions and uplink transmissions may be sent simultaneously on two frequency channels. In the case of TDD, the downlink and uplink share the same frequency channel. Downlink and uplink transmissions may be sent over the same frequency channel at different time intervals.

Thus, the wireless communication system 101 can include one or more base stations 110 that can support communication for multiple UEs 130, 132, 135, 137. The system can also include relay stations 120 that can improve the coverage and capacity of the system without the need for potentially expensive wired backhaul links. The relay station receives a signal from an upstream station (e.g., base station), processes the received signal to recover the data transmitted as the signal, generates a relay signal based on the recovered data, and sends the relay signal to the downstream station. It may be a " decoding and forwarding " station that can transmit to (eg, a UE).

For example, relay station 120 may communicate with base station 110 via a backhaul link and may appear as a UE to the base station. The relay station may also communicate with one or more UEs over an access link and may appear as a base station for the UE (s). However, relay stations typically cannot transmit and receive simultaneously on the same frequency channel. Therefore, the backhaul link and the access link can be time division multiplexed. Moreover, the system may have certain requirements that may affect the operation of the relay station. It may be desirable to support the efficient operation of a relay station in view of its transmission / reception restrictions as well as other system requirements.

5 shows a block diagram of a design of a base station / eNB 110, a relay station 120, and a UE 130. Base station 110 may transmit transmissions to one or more UEs on the downlink and may also receive transmissions from one or more UEs on the uplink. For the sake of simplicity, only the processing for transmissions to and from UE 130 is described below.

At base station 110, transmit (TX) data processor 510 may receive packets of data to transmit to UE 130 and other UEs, and process each packet according to the selected MCS (eg, encoding). And modulation) to obtain data symbols. In the case of HARQ, the processor 510 may generate multiple transmissions of each packet and may provide one transmission at a time. The processor 510 may also process control information to obtain control symbols, generate reference symbols for the reference signal, and multiplex the data symbols, control symbols and reference symbols. The processor 510 may further process the multiplexed symbols (eg, for OFDM, etc.) to generate output samples. Transmitter (TMTR) 512 may adjust (eg, convert to analog, amplify, filter, and upconvert) the output samples to generate a downlink signal, which is downlink signal to relay station 120 and UEs. Can be sent to.

At relay station 120, a downlink signal from base station 110 may be received and provided to a receiver (RCVR) 536. Receiver 536 adjusts (eg, filters, amplifies, downconverts and digitizes) the received signal to provide input samples. A receive (RX) data processor 538 may process the input samples (eg, for OFDM, etc.) to obtain received symbols. The processor 538 may further process (eg, demodulate and decode) the received symbols to recover control information and data sent to the UE 130. TX data processor 530 may process (eg, encode and modulate) the recovered data and control information from processor 538 in the same manner as base station 110 to obtain data symbols and control symbols. The processor 530 may also generate reference symbols, multiplex the data and control symbols with the reference symbols, and process the multiplexed symbols to obtain output samples. The transmitter 532 may adjust the output samples to generate a downlink relay signal, which may be sent to the UE 130.

At the UE 130, the downlink signal from the base station 110 and the downlink relay signal from the relay station 120 are received and adjusted by the receiver 552, processed by the RX data processor 554, and the UE The control information and data transmitted to 130 may be restored. Controller / processor 560 may generate ACK information for correctly decoded packets. Data and control information (eg, ACK information) to be transmitted on the uplink are processed by the TX data processor 556 and adjusted by the transmitter 558 to generate an uplink signal, which is the relay station. May be sent to 120.

At relay station 120, an uplink signal from UE 130 is received by receiver 536, adjusted and processed by RX data processor 538 to transmit data and control information transmitted by UE 130. Can be restored The recovered data and control information may be processed by the TX data processor 530 and adjusted by the transmitter 532 to generate an uplink relay signal, which may be transmitted to the base station 110. . At the base station 110, an uplink relay signal from the relay station 120 is received and adjusted by the receiver 516, processed by the RX data processor 518, and transmitted to the UE 130 via the relay station 120. It is possible to restore the data and the control information transmitted by the. The controller / processor 520 may control the transmission of data based on the control information from the UE 130.

Controllers / processors 520, 540, 560 may direct the operation at base station 110, relay station 120, and UE 130, respectively. The memories 522, 542, 562 may store data and program codes for the base station 110, the relay station 120, and the UE 130, respectively.

In an aspect, logical channels are classified into control channels and traffic channels. Logical control channels include a Broadcast Control Channel (BCCH), a DL channel for broadcasting system control information, a Paging Control Channel (PCCH), a DL channel for transmitting paging information, and one or more channels. Multicast Control Channel (MCCH), a point-to-multipoint DL channel used for transmitting Multimedia Broadcast and Multicast Service (MBMS) scheduling and control information for two MTCHs It includes. In general, after establishing an RRC connection, this channel is used only by UEs receiving MBMS (Note: old MCCH + MSCH). Dedicated Control Channel (DCCH) is a point-to-point bidirectional channel that transmits dedicated control information and is used by UEs having an RRC connection. In an aspect, logical traffic channels include a Dedicated Traffic Channel (DTCH), which is a point-to-point bidirectional channel dedicated to one UE for transmission of user information. In addition, logical traffic channels include a Multicast Traffic Channel (MTCH) for a point-to-multipoint DL channel for transmitting traffic data.

In one aspect, transport channels are classified into DL and UL. DL transport channels include a broadcast channel (BCH), a downlink shared data channel (DL-SDCH) and a paging channel (PCH), which support UE power saving (DRX cycle). PCH for this indication by the network to the UE is broadcast for the entire cell and mapped to PHY resources that can be used for other control / traffic channels. UL transport channels include a random access channel (RACH), a request channel (REQCH), an uplink shared data channel (UL-SDCH), and a plurality of PHY channels. PHY channels include a set of DL channels and UL channels.

DL PHY channels include:

Common Pilot Channel (CPICH)

Synchronization Channel (SCH)

Common Control Channel (CCCH)

Shared DL Control Channel (SDCCH)

Multicast Control Channel (MCCH)

Shared UL Assignment Channel (SUACH)

Acknowledgment Channel (ACKCH)

DL Physical Shared Data Channel (DL-PSDCH)

UL Power Control Channel (UPCCH)

Paging Indicator Channel (PICH)

Load Indicator Channel (LICH)

UL PHY channels include:

Physical Random Access Channel (PRACH)

Channel Quality Indicator Channel (CQICH)

Acknowledgment Channel (ACKCH)

Antenna Subset Indicator Channel (ASICH)

Shared Request Channel (SREQCH)

UL Physical Shared Data Channel (UL-PSDCH)

Broadband Pilot Channel (BPICH)

In one aspect, a channel structure is provided that maintains the low PAR characteristics of a single carrier waveform (channels are evenly spaced or continuous at any given time).

For the purposes of this document, the following abbreviations apply:

ACK Acknowledgment

AM acknowledged mode

AMD Acknowledgment Mode Data

ARQ Automatic Repeat Request

BCCH Broadcast Control CHannel

BCH Broadcast CHannel

C- Control-

CCCH Common Control CHannel

CCH Control Channel

CCTrCH Coded Composite Transport Channel

CP Cyclic Prefix

CQI Channel Quality Indication

CRC Cyclic Redundancy Check

CSG Closed Subscriber Group

CTCH Common Traffic CHannel

DCCH Dedicated Control CHannel

DCH Dedicated CHannel

DL Downlink

DSCH Downlink Shared CHannel

DTCH Dedicated Traffic CHannel

FACH forward link access channel

FDD Frequency Division Duplex

HARQ Hybrid Automatic Repeat Request

L1 Tier 1 (Physical Tier)

L2 Layer 2 (Data Link Layer)

L3 Layer 3 (Network Layer)

LI length indicator

LSB Least Significant Bit

MAC Medium Access Control

MBMS Multimedia Broadcast Multicast Service

MBSFN multicast broadcast single frequency network

MCCHMBMS point-to-multipoint control channel

MCE MBMS coordinating entity

MCH multicast channel

MCS Modulation Coding Scheme

Move Receiving Window

MSB Most Significant Bit

MSCHMBMS point-to-multipoint Scheduling CHannel

MTCHMBMS point-to-multipoint traffic channel

MSCH MBMS control channel

NAK negative acknowledgment

PCCH Paging Control CHannel

PCH Paging Channel

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

PDU Protocol Data Unit

PHICH Physical Indicator Signal Acknowledgment

PHYs physical layer

PhyCH Physical Channels

PUSCH Physical Uplink Shared Channel

RACH Random Access CHannel

RLC Radio Link Control

RRC Radio Resource Control

SAP Service Access Point

SDU Service Data Unit

SF Subframe

SHCCH Shared Channel Control CHannel

SN Sequence Number

SR Scheduling Request

SUFI FIeld

TCH Traffic Channel

TDD Time Division Duplex

TFI Transport Format Indicator

TM Transparent Mode

TMD Transparent Mode Data

TTI Transmission Time Interval

U- User-

UE User Equipment

UL UpLink

UM Unacknowledged Mode

UMD Unacknowledged Mode Data

UMTS Universal Mobile Telecommunications System

UTRA UMTS Terrestrial Radio Access

UTRAN UMTS Terrestrial Radio Access Network

VPLMN Visited Public Land Mobile Network

Embodiments described in detail herein refer to methods and apparatuses for applying hybrid automatic retransmission request (HARQ) procedures for transparent relays via relay stations 120.

For example, a transparent relay can be defined as a relay through relay station 120 where there are no independent control channels established between relay station 120 and the UE 130 that it is serving. Under this setup, the transparent relay station 120 does not need to transmit or receive a control channel from the UE 130. Instead, relay station 120 only needs to maintain a control channel with base station 110.

Unfortunately, the lack of control channels can result in a failure of the hybrid automatic retransmission request (HARQ) loop for LTE systems. It may therefore be advantageous to provide methods and apparatuses for enabling HARQ procedures for transparent relay station 120 and associated UE (s) 130.

Systems, apparatus, and methods for relay station 120 for use in a communication system having a base station 110 and a user equipment (UE) 130 are disclosed. The relay station 120 may decode and forward data packets between the UE 130 and the base station 110 served by the relay station, where the relay station does not establish a direct link with the UE 130. In addition, if relay station 120 receives information indicative of successful decoding of a data packet from relay station 120, then base station 110 provides a direct link between base station 110 and UE 130. Terminating the HARQ transmission indicates successful decoding of the data packet to the base station 110 such that the HARQ retransmission time is extended compared to direct communications between the base station and the UE.

Referring to FIG. 6, a method 600 for applying HARQ procedures for transparent relays for relay station 120 is described.

In one embodiment, anchor base station 110 may send an uplink (UL) assignment 605 to UE 130. For example, in the timeline of exemplary LTE, the UL assignment 605 is a subframe (SF) index of N? SF (N) may be included. The UE 130 may then transmit data to the anchor base station 110 later on the physical uplink shared channel (PUSCH) 610, such as PUSCH (N + 4). It should be appreciated that relay station 120 is sniffing UL assignment 605 and PUSCH data 610.

In the LTE system example, the LTE system may require the anchor base station 110 to send a Physical Indicator Signal Acknowledgment (PHICH) at N + 8, where four subframes are used for processing and scheduling. In the present embodiment, it may be assumed that similar decoding latency is required at relay station 120 to decode a UE transmission as compared to the decoding latency of base station / eNB 110 as an example.

Next, additional steps may be implemented for relay station 120 to exchange information with anchor base station 110 to confirm that anchor base station 110 transmission is properly acknowledged. In one example, at K milliseconds after decoding, relay station 120 may send a scheduling request (SR) 616 to anchor base station 110 (denoted as time (N + 4 + K)). Then, at L㎳ after the SR transmission, the anchor base station 110 may decode the SR of the relay station.

For example, to describe a physical indication signal acknowledgment (PHICH) timeframe, if x = K + L, the anchor base station 110 PHICH timeline may be pushed by x㎳.

If relay station 120 successfully decodes the UE transmission (ie, PUSCH data 610), relay station 120 transmits SR 616 to anchor base station 110 at N + 4 + K, thereby relay station 120 ) May indicate that the UE transmission has been successfully decoded. Relay station 120 may then monitor anchor base station 110 for transmission of physical indication signal acknowledgment (PHICH) and physical downlink control channel (PDCCH) as follows:

1. If anchor base station 110 decodes PUSCH data 610, anchor base station 110 draws an acknowledgment (ACK) as PHICH 620 at time (N + 8 + x) and assigns an allocation to the PDCCH. Transmit to 130. Allocation is intended for UE transmission at N + 8 + x + 4. Relay station 120 may then decode both PHICH and PDCCH and turn on UL RX at N + 8 + x + 4 to allow the relay process to restart.

2. On the other hand, if the anchor base station 110 did not decode the PUSCH data 610, the anchor base station 110 may acknowledge the acknowledgment (ACK) and the PDCCH as the PHICH 620 at time (N + 8 + x). Send an assignment to. However, the assignment is UL assignment 622 and is intended for relay transmission at N + 8 + x + 4. In this case, relay station 120 decodes the assignment, turns on UL TX at N + 8 + x + 4, and decodes the PUSH data (decoded by relay station 120) via UL 625. send.

3. Since there is no intermediate relay, the relay station 120 may use the timeline of the LTE system when transmitting to the Anger base station 110, and the relay station 120 may transmit the PUSCH data by independent coding. In addition, RS 120 may transmit PUSCH data consisting of redundancy bits of the original codeword transmitted by UE 130 to facilitate coupling at anchor base station 110. It should also be appreciated that the anchor base station 110 may possibly schedule parallel UE (s) 130 and relay station (s) 120 transmissions that may result in a collision of relay station (s) transmission function and reception function. do. Thus, if relay station 120 transmits to anchor base station 110 to assist in decoding previous PUSCH data, then the modulation coding scheme (MCS) selection of a new transmission of the UE should take into account the fact that relay station 120 is excluded. Also, if relay station 120 receives new PUSH data, the MCS selection of the new transmission of the UE should take into account the fact that relay station 120 is assigning new packet decoding.

On the other hand, if relay station 120 was unable to successfully decode the UE transmission (i.e., PUSCH data 610), relay station 120 may send a negative acknowledgment (NAK) to anchor base station 110; Or by not implying an SR by implicit NAK), the anchor base station 110 may transmit an anchor NAK to the UE 130 (eg, the anchor NAK is transmitted to the UE via PHICH at N + 8 + x). Then, the anchor base station 110 may retransmit the UL assignment (eg, at N + 8 + x + 4) to the relay station 120.

Referring to FIG. 7, FIG. 7 is a flowchart illustrating a process 700 for applying HARQ procedures for transparent relays to relay station 120. At block 702, the anchor base station 110 may send an uplink (UL) assignment for the UE 130. At decision block 703, process 700 determines whether relay station 120 successfully decoded the UL assignment. If it did not allocate successfully, process 700 ends (block 705). However, if successful, and if the UE sends PUSCH data to the anchor base station (block 710), process 700 then determines whether relay station 120 decoded the PUSCH data (block 712). ). If decoded, relay station 120 transmits an SR to anchor base station 110 (block 714). Next, process 700 determines whether anchor base station 110 has decoded PUSH data (block 716). If decoded, anchor base station 110 sends an ACK to UE 130 (block 718), and relay station 120 turns on UL Rx (block 720). If not, the anchor base station sends an ACK to the UE 130 (block 730), and the relay station 120 transmits the decoded PUSCH data to the anchor base station 110 via UL (block 732). On the other hand, if relay station 120 could not decode the PUSCH data (block 712), relay station 120 sends a NAK to anchor base station 110 (block 740) and anchor base station 110 Transmits a NAK to the UE (block 742), and the UE 130 retransmits the PUSCH data (block 744).

Referring to FIG. 8, for each UL transmission in another embodiment, anchor base station 110 performs two transmissions, one transmission for UE 130 and the other transmission for relay station 120. Can be scheduled. For example, anchor base station 110 may transmit a first UL assignment 802 to relay station 120 and a second UL assignment 804 to UE 130. For example, both UL assignments 802, 804 can be in the SF index (N). Then, the UE 130 may transmit the PUSCH data 810 at N + 4. If RS 120 decodes PUSCH data, RS 120 may transmit PUSCH data 820 at N + 8. However, if the relay station does not decode the PUSCH data, the relay station 120 may: A) be silent; Alternatively, B) NAK 822 may be transmitted to the anchor base station 110 to indicate a PUSCH decoding failure. For example, the NAK may be a new UL control channel. The anchor base station 110 may combine both transmissions of PUSCH data from the UE 130 and the relay station 120. In addition, the anchor base station 110 may transmit 824 an ACK or NAK over the PHICH (eg, at the SF index (N + 12)) to acknowledge or deny receipt of the PUSCH data from the UE. .

9, a method 900 for applying asynchronous HARQ procedures for downlink (DL) is described. In this embodiment, for LTE downlink (DL) allocation, the HARQ may be asynchronous such that each individual retransmission can be set up without coupling. This may allow individual scheduling of transmissions from anchor base station 110 to UE 130 and from relay station 120 to UE 130.

Referring to FIG. 9, the anchor base station 110 may send a physical downlink shared channel (eg, at index N) (eg, at index N) to transmit DL allocation and data to which the relay station 120 also sniffs. PDSCH) 902 may be transmitted. Based on this, anchor base station 110 may receive an ACK or NAK 904 from relay station 120 (eg, at N + 4) and an ACK or NAK 906 from UE 130. The anchor base station 110 then sends a pre-assignment 910 (eg, at N + 8) to inform the relay station 120 of the scheduling decision for transmission from the relay station 120 to the UE 130. Can be. However, as will be discussed, this pre-allocation 910 is an optional embodiment. The base station 110 then transmits a DL assignment 914 to the UE 130 and the relay station 120 sends the PDSCH 916 containing data to the UE 130 (eg, at N + 12). send. The UE 130 may then send an ACK or NAK 918 back to the anchor base station 110. It should be appreciated that the system 900 may loop between the pre-allocation 910, the allocation 914, the PDSCH 916, and the ACK / NAK 918 until the UE decodes the data.

However, in one embodiment, the transmission from relay station 120 to UE 130 (eg, PDSCH 916) may be prescheduled by anchor base station 110 to improve latency. In this case, pre-allocation 910 may be omitted to reduce latency. In this example, the relay station 120 transmission of the PDSCH 916, including the DL assignment 914 for the UE 130 and the data for the UE 130, may occur at N + 8. This is a trade-off between latency / control overhead and data efficiency. In addition, if relay station 120 can receive an ACK / NAK from UE 130, latency can also be reduced by using a synchronous HARQ between relay station 120 and UE 130. Tradeoffs between delay, control overhead, and data efficiency can be considered design and implementation considerations.

Other aspects of relay retransmission with a prescheduled transmission format may also be considered. For example, in one embodiment, this format can be adjusted based on the UE 130. In addition, the preconfigured transmission format may be based on UE channel quality indication (CQI) reporting. In addition, the preconfigured transmission format may be based on the original DL transmission format. Moreover, the preconfigured transmission format may be in the form of asynchronous HARQ retransmission of the original transmission. For example, using modulation coding schemes (MCS): the MCS may be the same, or the MCS may be changed, for example, given the same dimensions: 1) backhaul link> If it is an access link, the MCS selected for the first transmission may be higher than the transmission from the relay station 120 to the UE 130; 2) If the backhaul link <access link, then the MCS selected for the first transmission may be lower than the transmission from the relay station 120 to the UE 130; Or 3) if the dimension changes, the MCS can be adjusted accordingly. In another embodiment, the resource elements used for transmission from relay station 120 to UE 130 may be fixed or may be a function of original DL allocation. For example, example embodiments include the same size + same location, the same size + different time-frequency location, different size + same location, different size + different location.

Referring to FIG. 10, FIG. 10 is a flowchart illustrating a process 1000 for applying HARQ procedures for transparent relays for relay station 120 for an associated UE 130. At block 1002, anchor base station 110 may send downlink (DL) allocation and data that relay station 120 sniffs to UE 130. At decision block 1003, process 1000 determines whether relay station 120 has successfully decoded DL data. If successfully decoded, anchor base station 110 sends a pre-allocation to relay station 120 (block 1006). The anchor base station 110 then sends an assignment to the UE (block 1008). Relay station 120 then sends the decoded DL data to UE 130 (block 1010).

On the other hand, if the process 1000 in decision block 1003 determines that relay station 120 did not successfully decode DL data, relay station 120 sends a NAK to anchor base station 110 (block ( 1020)). The anchor base station 110 may then retransmit the DL allocation and data to the UE 130 (block 1024) and resume process 1000.

The controllers / processors 520, 540, 560 of FIG. 5 may direct operation at the base station 110, the relay station 120, and the UE 130, respectively, and the controllers / processors 520, 540, It should be appreciated that 560 may perform or direct the processes and methods 600, 700, 800, 900, 1000 of FIGS. 6-10, and / or other processes for the techniques described herein. . The memories 522, 542, 562 may store data and program codes for the base station 110, the relay station 120, and the UE 130, respectively.

It is understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design priorities, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in an exemplary order, but are not meant to be limited to the specific order or hierarchy presented.

Those skilled in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, instructions, information, signals, bits, symbols, and chips that may be referenced throughout the above description may include voltages, currents, electromagnetic waves, magnetic fields, or magnetic particles. , Optical fields or light particles, or any combination thereof.

Those skilled in the art will also appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be electronic hardware, computer software, or both. It will be appreciated that it can be implemented as a combination of. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented in hardware or software depends upon the design constraints imposed on the particular application and the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein are general purpose processors, digital signal processors (DSPs), application specific integrated circuits (DSPs) designed to perform the functions described herein. Implemented or performed by an application specific integrated circuit (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof Can be. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, eg, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other type of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integrated into the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more illustrative embodiments, the functions described may be implemented in hardware, software, firmware or any combination thereof. If implemented in software, these functions may be stored or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer readable media may carry desired program code in the form of RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or instructions or data structures. Or any other medium that can be used to store or otherwise accessible by a computer. Discs such as disks and discs used here include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVD), and floppy discs. disks and blu-ray discs, where disks typically reproduce data magnetically, while disks optically reproduce data by lasers. Combinations of the above should also be included within the scope of computer-readable media.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. . Thus, the present disclosure is not to be construed as limited to the embodiments set forth herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (44)

As a device,
Processor The processor comprising:
Decode and forward data packets between the base station and the UE served by a relay station that has not established a direct link with the user equipment (UE); And
Execute instructions for indicating to the base station successful decoding of the data packet;
If the base station receives information indicating successful decoding of the data packet from the relay station, the base station has a hybrid automatic repeat request (HARQ) retransmission time compared to direct communications between the base station and the UE. Terminating HARQ transmission on the direct link between the base station and the UE to extend; And
A memory configured to store the instructions;
Device. The method of claim 1,
Further comprising sending an acknowledgment (ACK) from the base station to the UE,
Device. The method of claim 1,
Further determining whether the base station has decoded the data packet;
Device. The method of claim 3, wherein
If the base station does not decode the data packet, further comprising transmitting the decoded data packet to the base station,
Device. The method of claim 1,
If the relay station does not decode the data packet, further comprising sending a negative acknowledgment (NAK) from the relay station to the base station;
Device. The method of claim 5, wherein
If the relay station does not decode the data packet, further comprising sending a negative acknowledgment (NAK) from the base station to the UE and retransmitting the data packet by the UE,
Device. As a method,
Decoding and forwarding a data packet between the base station and the UE served by a relay station that has not established a direct link with a user equipment (UE); And
Indicating to the base station successful decoding of the data packet;
If the base station receives information indicating successful decoding of the data packet from the relay station, the base station is further configured to extend the hybrid automatic retransmission request (HARQ) retransmission time as compared to direct communications between the base station and the UE. Terminating HARQ transmission on the direct link between the UE,
Way. The method of claim 7, wherein
Sending an acknowledgment (ACK) from the base station to the UE,
Way. The method of claim 7, wherein
Determining whether the base station has decoded the data packet;
Way. The method of claim 9,
If the base station does not decode the data packet, further comprising transmitting the decoded data packet to the base station,
Way. The method of claim 7, wherein
If the relay station does not decode the data packet, sending a negative response (NAK) from the relay station to the base station;
Way. The method of claim 11,
If the relay station does not decode the data packet, transmitting a negative acknowledgment (NAK) from the base station to the UE and retransmitting the data packet by the UE;
Way. As a computer program product,
Let at least one computer:
Decode and forward data packets between the base station and the UE served by a relay station that has not established a direct link with the user equipment (UE); And
A computer readable medium comprising code for causing the base station to indicate successful decoding of the data packet;
If the base station receives information indicating successful decoding of the data packet from the relay station, the base station is further configured to extend the hybrid automatic retransmission request (HARQ) retransmission time as compared to direct communications between the base station and the UE. Terminating HARQ transmission on the direct link between the UE,
Computer program stuff. The method of claim 13,
Further comprising code for causing at least one computer to send an acknowledgment (ACK) from the base station to the UE,
Computer program stuff. The method of claim 13,
Further comprising code for causing at least one computer to determine whether the base station has decoded the data packet;
Computer program stuff. The method of claim 15,
If the base station did not decode the data packet, further comprising code for causing at least one computer to transmit the decoded data packet to the base station;
Computer program stuff. The method of claim 13,
If the relay station does not decode the data packet, further comprising code for causing at least one computer to send a negative acknowledgment (NAK) from the relay station to the base station;
Computer program stuff. The method of claim 17,
If the relay station does not decode the data packet, further comprising code for causing at least one computer to send a negative acknowledgment (NAK) from the base station to the UE and to retransmit the data packet by the UE. ,
Computer program stuff. As a device,
Means for decoding and delivering a data packet between the base station and the UE served by a relay station that has not established a direct link with a user equipment (UE); And
Means for indicating to the base station successful decoding of the data packet;
If the base station receives information indicating successful decoding of the data packet from the relay station, the base station is further configured to extend the hybrid automatic retransmission request (HARQ) retransmission time as compared to direct communications between the base station and the UE. Terminating HARQ transmission on the direct link between the UE,
Device. The method of claim 19,
Means for sending an acknowledgment (ACK) from the base station to the UE,
Device. The method of claim 19,
Means for determining whether the base station has decoded the data packet;
Device. The method of claim 21,
Means for sending the decoded data packet to the base station if the base station did not decode the data packet;
Device. The method of claim 19,
Means for sending a negative acknowledgment (NAK) from the relay station to the base station if the relay station did not decode the data packet.
Device. The method of claim 23,
Means for sending a negative acknowledgment (NAK) from the base station to the UE and retransmitting the data packet by the UE if the relay station did not decode the data packet.
Device. A wireless communication method comprising:
Transmitting downlink (DL) allocation and data from the base station to the user equipment (UE); And
Determining whether the DL data is decoded by a relay station;
Wireless communication method. The method of claim 25,
When the DL data is decoded by the relay station, transmitting from the base station to the relay station a pre-allocation.
Wireless communication method. The method of claim 26,
Transmitting the decoded DL data from the relay station to the UE,
Wireless communication method. The method of claim 25,
If the DL data is not decoded by the relay station, transmitting a not acknowledged signal from the relay station to the base station;
Wireless communication method. 29. The method of claim 28,
Retransmitting the DL allocation and data from the base station to the UE,
Wireless communication method. A relay station for use in a communication system having a base station and user equipment (UE),
A processor configured to execute instructions for decoding downlink (DL) data sent from the base station to the UE; And
A memory configured to store the instructions;
Relay station. 31. The method of claim 30,
If the DL data is decoded by the relay station, further comprising receiving a pre-allocation from the base station,
Relay station. The method of claim 31, wherein
Further comprising transmitting the decoded DL data to the UE,
Relay station. 31. The method of claim 30,
If the DL data is not decoded by the relay station, further comprising sending a negative acknowledgment (NAK) signal to the base station,
Relay station. The method of claim 33, wherein
The base station retransmits DL allocation and data to the UE,
Relay station. As a device,
Means for decoding downlink (DL) data transmitted from a base station to user equipment (UE),
Device. 36. The method of claim 35 wherein
Means for receiving a pre-allocation from the base station when the DL data is decoded by a relay station,
Device. The method of claim 36,
Means for transmitting the decoded DL data to the UE,
Device. 36. The method of claim 35 wherein
Means for sending a negative acknowledgment (NAK) signal to the base station if the DL data is not decoded by a relay station;
Device. The method of claim 38,
The base station retransmits DL allocation and data to the UE,
Device. As a computer program product,
A computer readable medium comprising code for causing at least one computer to decode downlink (DL) data transmitted from a base station to user equipment (UE),
Computer program stuff. The method of claim 40,
If the DL data is decoded by a relay station, further comprising code for causing at least one computer to receive a pre-allocation from the base station,
Computer program stuff. 42. The method of claim 41 wherein
Further comprising code for causing at least one computer to transmit the decoded DL data to the UE,
Computer program stuff. The method of claim 40,
If the DL data is not decoded by a relay station, further comprising code for causing at least one computer to send a negative acknowledgment (NAK) signal to the base station;
Computer program stuff. The method of claim 43,
The base station retransmits DL allocation and data to the UE,
Computer program stuff.

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